Abstract: Backyard poultry rearing is an important venture and integral part of mixed farming in most of the developing countries of world. Very scarce reports regarding the effects of parasites on free ranging birds are available from India. The present study was designed to investigate the prevalence of helminth parasites in the backyard poultry farming in the northern, humid and subtropical region of India. A total of 120 gut specimens and 600 faecal samples of backyard poultry were collected from different villages and analysed for parasitic worm loads and different egg/ova types. Furthermore, a random field trial on 40 birds reared in backyard poultry system was carried out to determine the effect of fenbendazole treatment on the parasitic load and production performance. On gut examination, the most common nematodes found were, Ascaridia galli (20%), Heterakis gallinarum (10.83%), Capillaria spp. (5%) and Cheilospirura hamulosa (1.67%) while the cestodes were Raillietina tetragona (9.16%), R. echinbothrida (5%), Hymenolepis spp. (5%), Cotugnia digonopora (3.33%) and R. cesticillus (2.5%). The faecal examination showed higher incidence of A. galli (19.16%), H. gallinarum (9.5%), Capillaria spp. (3.5%), Trichostrongylus tenuis (2.5%), Raillietina spp. (16.16%), Eimeria spp. (5.33%) and mixed infections (6.67%). Treatment with fenbendazole was found to reduce mortality (15%) as compared to untreated (30%) groups. Moreover, fenbendazole treated birds gained significantly steadily weights (r = -0.35) as compared to untreated group (r = -0.019). The study is first in its nature in providing the valuable information regarding prevalence of endoparasites based on faecal examination in backyard poultry from the Jammu region. This information will essentially be helpful for the researchers and local veterinarians to develop strategies for both treatment and control of these endoparasites affecting poultry.